1. Field of the Invention
This invention relates to a method for brightening the electrodeposits of zinc from zinc electroplating baths such as the cyanide, zincate or chloride baths.
2. Description of the Prior Art
It is well-known that bright zinc electroplated coatings cannot be obtained without using a zinc electroplating bath which contains a brightener. Consequently, various types of brightener additives for zinc electrodepositing processes have been widely investigated. Included among those brighteners are aliphatic aldehydes, aryl aldehydes, heterocyclic aldehydes, derivatives or organic compounds containing a nitrogen or a sulfur atom and the reaction products of specific aliphatic amines with compounds containing alkyl or aryl radicals.
The brightener additives which have been developed in the prior art are satisfactory only for use in a specific electroplating bath such as cyanide baths, but are not presently satisfactory for use in other baths such as zincate baths. None of the brightener additives known presently are satisfactory for use in two or more types of electroplating baths.
A need therefore continues to exist for a method of brightening zinc electrodepositions which is useful in more than one type of zinc electroplating baths.